RFR: 8283575: Check for GNU time fails for version >1.7

[Erik Joelsson]

On Wed, 23 Mar 2022 16:22:55 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Looks okay, provided you tested with some version of GNU [Tt]ime.

Thanks! I hit this while trying to use GNU time on my mac to get LOG=profile to work, to profile compilation times of individual compilation units. I built latest (1.9) from source and it didn't detect it (same with 1.8). With this patch it works as expected.

> Is double square bracket some sort of escaping? Haven't seen it before.

Yes, it's escaping needed to use brackets in autoconf/m4. Sometimes we put the escape sequence around the complete expression, sometimes we just double up like I did here. You should be able to find several occurrences through out our autoconf scripts.

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PR: https://git.openjdk.java.net/jdk/pull/7925